Self propagating high temperature synthesis, or combustion synthesis, has become an important process for bonding materials. Typically a combustion synthesis material, possibly combined with other compounds is interspersed between two parts that are to be bonded together. The combustion reaction is initiated by heating the starting materials to their ignition temperature, whereupon combustion occurs and spreads throughout the combustion synthesis materials. Once initiated, the exothermic combustion reaction creates product material which ultimately binds the parts together.
For example, a high melting point ceramic may be formed from the combustion materials and the other compounds that are present, which quickly freezes binding the parts together. Advantages of combustion synthesis include high product purity and relative simplicity of the overall process. Refurbishment of carbon-carbon brake disks has been achieved by use of combustion synthesis to bond carbon-carbon materials.
A major problem in combustion synthesis is to uniformly heat the combustion agents when bonding large surface areas. This is necessary in order to create a combustion product that is entirely in the liquid phase at one moment in time. The problem has been approached in the past by applying large electrical energies to the parts being bonded. The current flows through both the combustible materials and the parts to be bonded, heating both until the ignition temperature is achieved.
Another method has been to heat both the materials to be bonded, and the combustion synthesis powder to above the ignition point of the powders. It is generally not necessary to heat the parts to be bonded to the ignition temperature, only the combustion synthesis materials used to create combustion products need to reach the ignition temperature. Nevertheless it has proven difficult to uniformly heat large areas to create a combustion product that is entirely in the liquid phase at once. Accordingly, there is a need in the art for improved methods of combustion synthesis which can uniformly and efficiently heat large areas to an ignition temperature.